Johnstown, Colorado 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

103
FXUS65 KBOU 091127
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
527 AM MDT Sat May 9 2026

.KEY MESSAGES...

- Scattered afternoon and evening showers/thunderstorms (40-50%)
  for the northeastern plains on today.

- Summerlike warmth and drier weather next week, with highs in the
  80s for the lower elevations.

&&

.DISCUSSION /Through Friday/...
Issued at 210 AM MDT Sat May 9 2026

One more day of scattered rain showers and possibly thunderstorms
before a more quiet weather pattern takes over for next week.
Saturday will be warm, with forecasted high temperatures up to the
mid-to-high 70s for the plains, and 50s-60s for mountains and
valleys. By mid-afternoon, there remains 40-50% chance for scattered
convection across the northeastern plains due to a shortwave
trekking across northern Colorado. Modeled Skew-T soundings favor
high-based showers and thunderstorms capable of producing gusty
outflow winds, given modest DCAPE values. In addition, there is a
chance for small hail, as MUCAPE is expected to build through the
afternoon, with decent shear in place.

A cold front is progged to move through the forecast area Saturday
evening, which will bring gusty northeast winds up to 30-40 mph at
times. This front will also bring a brief chance (30-40% chance) of
light rain showers to the foothills and the Denver metro. Aside from
localized patchy fog in the morning, Sunday should see dry
conditions and more seasonal temperatures, with forecasted highs in
the mid-to-high 60s.

By next week, an upper level ridge will build over the southwestern
U.S. with warmer temperatures and mostly dry conditions expected.
Ensemble guidance continues to be in good agreement of temperatures
reaching 10 to almost 20 degrees above seasonal values, with highs
in the 80s (and even low 90s in the northeastern plains) across the
plains Monday and through the weekend. Heat should peak on
Wednesday, as the mid-level thermal ridge is progged over Colorado
by that time. It is interesting to note that some GEFS and ECMWF
ensemble solutions do have 89-91 dg F as the high temperature for
KDEN on Wednesday. If we do get up to 90 dg F on Wednesday, that
would tie our current high temperature record set in 1915. Besides
the heat, elevated-to-critical fire weather conditions are possible
Monday due to relative humidity values in the the low teens by the
afternoon, with winds gusting up to 25-30 mph at times.

&&

.AVIATION /12Z TAFS through 12Z Sunday/...
Issued at 526 AM MDT Sat May 9 2026

VFR conditions expected through Saturday evening. Drainage flow
expected to continue through 14Z for DEN and BJC, while APA will
stay light and VRB for the next few hours (varying between
southwest and southeast). Winds will become more westerly by
14Z/15Z and turn more northwesterly by 17Z at all terminals. Gusts
up to 20-25 kts are possible, particularly in the afternoon and
into the early evening. After that, a cold front will move across
the area and reach DEN and BJC by 01Z (by 02Z for APA). Gusty
northeasterly winds behind the front will likely reach up to 35
kts briefly.

Behind the front, MVFR conditions are likely through Sunday
morning, with a chance for IFR conditions between 04Z-09Z.
Ceilings will drop to 1000 ft, and possibly dropping to 800 ft
with the arrival of rain showers. For now, have a PROB30 for that
time. Expect ceilings to gradually improve after 12Z and through
Sunday morning, with VFR conditions returning by 18Z.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

DISCUSSION...MAI
AVIATION...MAI